Discharge tube



June 4, 1929. L.. sZlLARD 1,715,874

DI SCHARGE TUBE Filed Oct. 28, 1925 2 Sheets-Sheet l June 4, 1929. L,SZILARD 1,715,874

DISCHARGE TUBE Patented June 4, 1929.

UNITED STATES PATENT GFFICE.

LEO SZILARD, OF BERLIN-DAHLEM, GEICMANY, ASSIGNOR TO SIEMENS-SCHUCKERT-WERKE GESELLSCHAFT MIT BESCHRANKTER HAFTUNG, 0F SIEMENSSTADT, NEARBERLIN, GERMANY, A CORPORATION 0F GERMANY.

DISCHARGE TUBE.

Application led October 28, 1925, Serial No. 65,394, and in GermanyNovember 5, 1924.

My invention refers to thermionic discharge tubes provided with meansfor controlling the electron current between the anode and cathode, andit refers in part-icular to the type of discharge tubes in which, forthe purpose of obtaining a large current between the anode and cathode,an arc-like discharge occurs at the cathode.

One of the objects of my invention is to provide an electric dischargetube which is suitable to furnish a heavy current between the anode andcathode which can be effectively controlled by a controlling device.

A further object of the invention is the placing of the anode into oneof the vapor spaces of a mercury vapor pump (either into the vaporizingspace or into the vapor condensing space) and to arrange the controlmeans of the anode current in the low pressure or vacuum chamber of thepump.

Lastly an object of the invention is in arranging in tubes of the abovedescribed character the anode in the vapor space of one mercury vaporpump and the cathode in the vapor space of a second mercury pump and tocontrol the current between the anode and cathode in an evacuated-spacewhich is common to the two pumps.

I have illustrated in the accompanying drawings two forms in which myinvention may be reduced to practice, without thereby wishing to limittheforms in which my invention may be effectively carried out. In thesedrawings- Fig. 1 represents a partial longitudinal vertical section andpartlally a view of a pair of Velectric discharge vessels in accordancewith the present invention and Fic'. 2 represents a modification thereofin which one vessel is made of annular shape sulit-able to surround theother discharge vesse Referring to Fig. 1, l represents the vaporizingchamber of a mercury vapor jet pump, 2 is the condensing chamber of thepump and 3 represents the nozzle. 4 is the return pipe connectionthrough which the mercury 12 which has been condensed in chamber 2 isreturned into chamber 1. Chamber 2 is jacketed as shown at 13 andsuitable cooling fluid is led through the jacket for the purpose ofcondensing the mercury in chamber 2. The mercury in vaporizing chamber 1may be continuously vaporized by heating the mercury 10 in the lowerportion of the chamber by any suitable means known in the art.

A second similar mercury vapor jet pump 1s provided consisting o thevaporizing chamber 5, a condensing chamber 7 and the nozzle 6,condensing chamber 7 being similarly cooled by a jacket 13 as thepreviously described chamber 2. The mercury 12 which condenses inchamber 7 is also similarly returned to the vaporizing chamber 5 bymeans of a return pipe 4, and the lower portion of chamber 5, like thatof chamber. 1, is assumed to be heated by suitable known means. Betweenthe two pumps extends a suction chamber 8, preferably also acketed asshown, this chamber being in common with both vaporizing chambers 1 and5, so that both pumps tend to evacuate chamber 8. Consequently, asubstantially lower pressure exists in chamber 8 than in chambers 1 and5.

The mercury 10 in chamber 1 constitutes the cathode of the system andthe mercury 11 in chamber 5 constitutes the anode. 19 and 20 arerespectively the two inlead connections for the cathode and the anode.With low loads a gas discharge, such as an are discharge, may preferablyalso be maintained in the vapor jet between chambers 1 and 2, by meansof an auxiliary source of current which may be connected between theterminals 19 and 15 to have a sufficient number of negative chargecarriers available for the current passage. Only the terminals 19 and15, to which this auxiliary source may be connected are shown.

In the vacuum chamber 8 is disposed a control grid 9 which has an inleadconnection 18 and which is arranged in that chamber so that it stands inthe path of the current passing between the cathode 10 and the anode 11.Since now in view of the greater pressure prevailing in the vaporizingchamber 1, an arclike discharge occurs, a sufficient number of electronsare discharged from cathode 10 which are drawn over to the anode by wayof the two nozzles 3 and 6. The positive charges which compensate thenegative space charge in chamber 8 yare produced in the spaces 5 and 7and in the vapor jet passing from space 5 into space'7, this impactionization belng due to the greater pressure existing in spaces 5 and 7than in space 8. Consequently, the current density of the discharge tubeis very large owing on one hand to the particular form of the cathodeand on the other hand to the removal of the effect of the space charge.Notwithstanding, however, a very eEective controlof the anode current ispossible, since the controllgrid 9 is arranged in a space 8 which is sciently evacuated to make the control'action effective.

In the modification shown in Fig. 2, the mercury jet pump which containsthe cathode 10 is given an annular form which surrounds a centrallylocated mercury pump of the same character as that shown on the righthand side in Fig. 1. The central chamber in Fig. 2 contains the anode 11whereas the bottom of the annular pump p contains the cathode 10. Theinleads 19 and 20 are arranged similar to the mannershown in Fig. 1. InFig. 2, 21 constitutes the annular vaporizing chamber for the cathodemercury, 22 a correspondingly annular vapor condensing chamber. 24 isthe return conduit for the mercury 12, condensed in chamber 22, to thevaporizing chamber. 25 and 27 are respectively the vaporizing andcondensing chambers of the central pump which contains anode 11 in thebottom of chamber 25 and 34 is the return conduit for the mercury 12,condensed in chamber 27, to the vaporizer 25. 23 and 26 are respectivelythe nozzles of the annular and the central pump, nozzle 23 being in thiscase also of annular shape, surrounding the central nozzle 26. Thecommon suction or vacuum chamber of the two pumps is shown at 28 andaccordingly is of circular shape, containing the cylindricalcontrol grid29. The manner of operation of this pump system is exactly the same asthat of the lpump system shown in Fig. 1. Also in this case the cathodeand anode mercury may be vaporized by any suit- .able means known tothose skilled in the art.

Various other modifications or forms of the pumps may be arrangedwithout departing chambers.

2. A thermionic discharge device having a dischar-ige chamber throughwhich an electronic 'scharge may occur, means for mainmiaou tainin saidchamber evacuated and means in said c amber for controlling thedischarge, an anode chamber containing an anode and a gas whose pressureis higher than the pressure existing in'said discharge chamber,during'the operation of the device, said evacuation maintaining meanscomprising a cathode chamber containing a cathode and a gas whosepressure is higher than the pressure existing in said discharge chamber,and connections between said discharge chamber and said two ,l

other chambers. v

3. A thermionic discharge device having a discharge chamber throughwhich an electronic discharge may'occur, means constituting a cathodefor maintaining said chamber evacuated and means in said chamber forcontrolling the discharge, an anode chamber cona gas whose pressure ishigherthan the pressure existing in said dischar e chamber during theoperation of the devlce, said evacuation maintaining means comprising acathode chamber containing a cathode and a as of suiiicient ressure torender an arc scharge possiblia at the cathode and connections betweensaid discharge chamber and said two other chambers.

5. Athermionic discharge device having a discharge chamber through whichan electronic discharge may occur, means constituting a cathode formaintaining said chamber evacuated, a control grid in said chamber forcontrolling the electronic discharge therethrough, an anode chambercontaining an anode and a gas whose pressure is greater than thepressure in said discharge chamber during the operation of the deviceand a connection between said two chambers.

6. A thermionic discharge device comprising a mercury vapor pump havinga vaporizing chamber, a vapor condensing chamber and a high vacuumchamber and suitable connections between said chambers, said vaporizingchamber containing an anode and mercury vapor of a pressure sufficientto preventY the occurrence of negative electronic space charges in thehivh vacuum chamber, and a control element disposed in saiLhigh vacuumchamber for controlling an electron current flowing through said chamberto said anode.

7. An electronic discharge device comprising two mercury vapor (pumps,each having a vaporizing chamber an a vapor condensing chamber and ahigh vacuum chamber common to both pumps, thefvaporizing chamber of onepump containing a mercury anode and vapor of suficient pressure topreyent the occurrence of negative electronic space charges in said highvacuum chamber, the Vaporizing chamber of the other pump containing amercury cathode and vapor of sufficient pressure to render an arcdischarge at said cathode possible, said vacuum chamber containing acontrol electrode and having a suiciently high vacuum to control bymeans of said electrode the electron current flowing from the cathodethrough said chamber to the anode.

In testimony whereof I affix my signature.

LEO SZILARD.

